This invention relates generally to printers, and more specifically to printing devices and techniques for monochrome and color printers capable of achieving high quality resolution.
High quality printers are typically characterized by numbers indicating their resolution in dots per inch (dpi). This resolution is usually described in the context of a two dimension coordinate system where one number indicates the resolution in the x-axis (as used herein, x-axis means the carriage scan axis for a swath printer), and another number indicates the resolution in the y-axis (as used herein, y-axis means the media advance axis for a swath printer). Thus, a resolution of 300/300 dpi generally indicates a carriage-scan axis resolution of 300 dots per inch and a media-advance axis resolution of 300 dots per inch. If only a single dpi number is given, it is assumed the dpi in both axes are equal.
The resolution of a printhead is primarily determined by the actual printout dot size as it appears in a printout.
Hewlett-Packard has developed a 600 dpi inkjet pen for producing a very high resolution printout. One embodiment of this pen is described in Hewlett-Packard's U.S. Pat. No. 5,278,584, by Brian J. Keefe, et al., entitled INK DELIVERY SYSTEM FOR AN INKJET PRINTHEAD, incorporated herein by reference. The nozzle array of this 600 dpi pen contains 300 nozzles and prints a swath approximately one-half inch wide along the x-axis. Some of Hewlett-Packard's color printers will include a scanning carriage housing the 600 dpi pen, containing black ink, as well as one or more color inkjet pens. Currently these color inkjet pens have a resolution of 300 dpi and a width on the order of one-third inch.
The particular alignment of the 600 dpi and 300 dpi resolution printheads in the carriage as well as the particular alignment of the printed high resolution dots and lower resolution dots can be selected to achieve certain characteristics and advantages.